江淮梅雨暴雨的水汽源地及其输送通道

DIAGNOSIS OF ROLE OF MOISTURE SOURCES AND PASSAGES IN MEIYU RAINGUSH GENESIS

根据Ｔ４２客观分格网格点资料计算了１９９１年７月１０日０８时～１１日０８时江淮地区梅雨暴雨过程中水汽输送等物理量，以此分析水汽来源及其输送通道。结果表明，江淮地区梅雨暴雨水汽主要来自主加拉湾和南海及其以东地区。江淮梅雨区在８５０～５００ｈＰａ层有两个重要水汽源地，而地面到８５０ｈＰａ更重要的水汽源地是南海。南海的水汽主要靠西南及东南季风输送至暴雨区；而孟加拉湾水汽除通过印度季风低压向上输送至８５０ｈＰａ以上再由西南气流输送到江淮地区外，还通过季风低压南侧的偏西气流经中南半岛输送到南海及以东地区与东南季风汇合后，向北输向江淮地区。另外，在印度上空还有一支偏西南气流沿喜马拉雅山南麓携水汽向东流到了江淮地区的梅雨暴雨区上空。

Based om T─42 spectral model objectively analyzed gridded data,calculation is doneof all physical quantities associated with moisture transfer during the Changjiang-Huaihe Meiyuraingush event from 0800 BST July 10 to 0800 July 11,1991,followed by study of the moisturesources and passages.Results suggest that the water comes largely from two sources,one at theBay of Bengat and the other over the South-China Sea and area to the east;the rainband has twovital vapor sotirces at 850～500hPa layer with a still more important one at the Sea which offerswater for the raingush mainly through SW and SE monsoon;water fron the Bay of Bengal has itspart transported upward to levels higher than 850hPa with the aid of the Indian monsoondepression and further carried by SW flow into the rainbeolt and anothe rpart transferred by west-erly flow on the south side of the monsoon depression via the Indo-China peninsula into the Seaand area to the east,confluencing with SE monsoon and advancing northward into theChangjiang- Huaihe drainage .Besides,southwesterly flow over India carries water towards theeast alongside the sotith foot of the Himalayas into the Meiyu rainstorm region.